my issue is that how can i program multiple pins to be set as an output without the need of writting, pinMode function 100 times and digitalWrite function 200 times if i want the 100 solenides to be tuned on and then off..

for( i ; i=45; i++){pinMode( pinname , OUTPUT) }then another for loop for the second and third arduinos?

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Are you planning on banging all 100 solenoids on and off at the same time?

lol.... yes for example at the beginning of my graphical water show i want all the solenoids to be opened at once so that the water falls as a curtain and then i want to manipulate them so that they can give me a desired drawing or a letter etc...

lol.... yes for example at the beginning of my graphical water show i want all the solenoids to be opened at once so that the water falls as a curtain and then i want to manipulate them so that they can give me a desired drawing or a letter etc...

Nothing you're saying so far gives me any confidence that either the hardware or software required for this project is within your capabilities.

For what it's worth, I would have thought that a single Arduino using shift registers to drive your large array of driver circuits would be the most practical approach, since it avoids needing to synchronise activities across multiple Arduinos. Have you designed the driver circuits yet and figured out how you're going to build and then power 100 of them?

I only provide help via the forum - please do not contact me for private consultancy.

2. what does "single Arduino using shift registers to drive your large array of driver circuits" mean? or how can i use a single arduino to control such number of solenoids?

I think the second question makes my point about the first.

1/ I mean that your explanation of what you're planning to do gives me no confidence that you understand the software and hardware design issues that you would need to solve.

2/ I mean the number of Arduinos is one.The Arduino uses shift registers (probably more than one) to drive multiple outputs from a single pin. The outputs will need to be amplified via driver circuits before they would be able to power your solenoids. That means you're needing a lot of driver circuits. Which implies you need to either spend a significant amount of money buying them, or design and build your own. Given your question "what does it mean" I'm guessing that you would not find it easy to design and build your own driver circuits.

I only provide help via the forum - please do not contact me for private consultancy.

if what u mean by the driver circuit is not the mosfets and bybass diodes which will be connected to the solenoids then i have no idea of what drivers mean.... if it is what u mean then there is no problem with the drivers ...... the problem is with the shift register stuff..... how can i program multiple outputs on one pin? that's what i meant by question number 2

and by the way maybe the use of mosfets not the best idea therefore we are planning on using solid state relays